Dihydroperimidine squarylium dyes are described in J. CHEM. SOC., CHEM. COMMUN., 452-454 (1993) and U.S. Pat. No. 5,380,635. U.S. Pat. No. discloses dyes having the following nucleus: ##STR2##
The known dihydroperimidine squarylium dyes have an absorption maximum at a wavelength of about 780 nm to 830 nm. The dihydroperimidine squarylium dyes can be advantageously used as a near infrared filter dye.
A silver halide photographic material is usually processed in an automatic developing machine. The developing machine has a detecting mechanism, which emits an infrared ray to detect insertion of the silver halide photographic material. The mechanism sends a signal of insertion to the developing machine, which then starts development of the photographic material. Recently, it is difficult to detect the insertion, because the amount of silver halide contained in the photogrpahic material tends to be decreased. Japanese Patent Provisional Publication No. 3(1991)-211542 proposes adding a dye having absorption in the infrared region to the photographic material to detect the photogrpahic material. Further, Japanese Patent Application No. 7(1995)-269097 proposes adding solid dispersion of an infrared absorbing dye to the photogrpahic material.
The infrared ray emitted from the detecting mechanism usually has a wavelength of longer than 850 nm. On the other hand, the above-mentioned known dihydroperimidine squarylium compounds have an absorption maximum at not longer than 850 nm. Accordingly, it is not suitable to use the known dihydroperimidine squarylium compounds to detect a photographic material. Further, it is difficult to adjust the absorption maximum of the known dihydroperimidine squarylium compounds.